51. The osmotic pressure of a solution is:
A. Directly proportional to the temperature
B. Directly proportional to the volume of solvent
C. Inversely proportional to the temperature
D. Independent of temperature
Answer: A. Directly proportional to the temperature
Explanation:
Osmotic pressure is directly proportional to the absolute temperature (T) and the number of solute particles in the solution, as given by the formula:
π=iCRTπ=iCRT
where ππ is osmotic pressure, ii is the van’t Hoff factor, CC is concentration, and TT is temperature.
52. When the solute-solvent interactions are weaker than the solute-solute and solvent-solvent interactions, the solution shows:
A. Positive deviation from Raoult’s law
B. Negative deviation from Raoult’s law
C. No deviation from Raoult’s law
D. Ideal behavior
Answer: A. Positive deviation from Raoult’s law
Explanation:
When solute-solvent interactions are weaker, the components escape more easily, resulting in a higher vapor pressure than predicted by Raoult’s law. This leads to positive deviation.
53. The colligative property that causes the freezing point of a solution to be lower than that of the pure solvent is called:
A. Freezing point elevation
B. Freezing point depression
C. Boiling point elevation
D. Vapor pressure lowering
Answer: B. Freezing point depression
Explanation:
Freezing point depression is the decrease in the freezing point of a solvent when a solute is dissolved in it. This is a colligative property dependent on the number of solute particles.
54. If a solution follows Raoult’s law, it is classified as:
A. An ideal solution
B. A non-ideal solution
C. A supersaturated solution
D. A saturated solution
Answer: A. An ideal solution
Explanation:
A solution that obeys Raoult’s law at all concentrations and temperatures is considered an ideal solution. In such solutions, solute-solvent interactions are similar to solvent-solvent and solute-solute interactions.
55. When 1 mole of NaCl is dissolved in water, it dissociates into:
A. 1 particle
B. 2 particles
C. 3 particles
D. 4 particles
Answer: B. 2 particles
Explanation:
NaCl dissociates into two ions in water: Na⁺ and Cl⁻. Thus, 1 mole of NaCl produces 2 particles in the solution.
56. The effect of adding a non-volatile solute to a volatile solvent is:
A. Elevation in boiling point
B. Depression in freezing point
C. Lowering of vapor pressure
D. All of the above
Answer: D. All of the above
Explanation:
The addition of a non-volatile solute to a volatile solvent lowers the vapor pressure, elevates the boiling point, and depresses the freezing point. These are colligative properties that depend on the number of solute particles.
57. Colligative properties are related to:
A. The physical properties of the solvent
B. The chemical properties of the solute
C. The number of particles in the solution
D. The nature of the solute particles
Answer: C. The number of particles in the solution
Explanation:
Colligative properties depend on the number of solute particles in the solution, regardless of their chemical or physical nature.
58. Raoult’s law applies to which of the following solutions?
A. Dilute solutions only
B. Concentrated solutions only
C. Ideal solutions only
D. Solutions of electrolytes only
Answer: C. Ideal solutions only
Explanation:
Raoult’s law is strictly followed by ideal solutions where the interactions between solute and solvent are similar to those between solvent molecules and between solute molecules.
59. The boiling point of an ideal solution is higher than that of the pure solvent because:
A. The solute increases the vapor pressure of the solution
B. The solute lowers the vapor pressure of the solution
C. The solute raises the freezing point of the solution
D. The solute decreases the osmotic pressure
Answer: B. The solute lowers the vapor pressure of the solution
Explanation:
When a solute is added to a solvent, the vapor pressure of the solution decreases. This leads to a higher boiling point since the solution must be heated more to reach the point where its vapor pressure equals atmospheric pressure.
60. In a solution of an electrolyte, the van’t Hoff factor (i) is greater than 1 because:
A. The solute molecules dissociate into ions
B. The solute molecules form complexes
C. The solvent dissociates into ions
D. The solute molecules undergo association
Answer: A. The solute molecules dissociate into ions
Explanation:
The van’t Hoff factor (i) is greater than 1 for electrolytes because they dissociate into ions, increasing the number of solute particles in the solution.
Leave a comment